Polishing



Patented Nov. 8, 1932 I UNITED STATES PATENT OFFICE FREDERICK LACK, OFEAST ORANGE, 'NEW JERSEY, ASSIGNOR TO DU PONT VISCOLOID COMPANY, OFWILMINGTON, DELAWARE, A CORPORATION OF DELAWARE POLISHING Io DrawingThis invention relates to the polishing of articles, and moreparticularly to the polishing of articles by the tumbling-barrel methodor the equivalent. While not confined in its application thereto, it isparticularly adv-an synthetic resin, vegetable ivory, and the like.

In the polishing of articles of the general character indicated, it isdesirable to tumble them in the presence of a mild abrasive, such forexample as kieselguhr, a carrier for the abrasive, such for example, assmall elements of wood to which the abrasive can be adhered, and aspecies of adhesive for adhering the abrasive to the carriers, such forexample as wax. In this method of polishing there is, unless the same becorrected, the difiiculty that the adhesive adheres to the articlesbeing polished, so that, when the articles are discharged from thetumbling barrel they carry a cloud of material which dulls the lusterand which must be removed from the articles by an operation additionalto the tumbling; and such an additional operation, of course, adds to-the cost of the articles in handling expense, factory equipment andproduction time. Furthermore, even when the cloud has been removed, thearticles do not yet have the high finish which should result from apolishing operation.

I have devised a method of the general character indicated which notonly provides for a generally tumbling operation but, furthermore andparticularly, provides that the articles, when discharged from thetumbling barrel, will not only be free from the undesirable clouding butalso will have that high gloss which should result from fine polishing.

One object of the invention is to provide a polishing method wherebyarticlesmay be polished rapidly and at low cost. A further object is toprovide a method whereby the articles will be produced free from cloudand with a proper gloss. A further object is to provide suitablesolutions or mixtures for associating the abrasive to be used forpolish- Application filed. February 11, 1930. Serial No. 427,657.

ing, with the articles to be polished and with whatsoever carriers maybe used for the abrasive. To these ends, and also to improve generallyupon methods and solutions of the general character indicated, myinvention consists in the various matters hereinafter described andclaimed.

In general, my invention comprises tumbling the articles to be polishedin a tumbling barrel, together with abrasive, carriers for the abrasive,and a medium for associating the abrasive with the carriers. and thearticles. As a particular feature, the invention comprises cooling thearticles to room temperature somewhat prior to the completion of thetumbling, and while they are yet contained in the barrel and closelyassociated with the abrasive and the medium, thus to dissipate the heatgenerated during the tumbling; and continuing the tumbling action for ashort time while they are cool. I have found that this cooling in somemanner over- 1 comes and eliminates the objectionable clouding, and thefinal tumbling burnishes the articles.

I now proceed to a detailed description of the invention, it beingunderstood that such descriptionis given by way of example merely, andnot by way of limitation, and it being further understood that detailssuch as proportions of ingredients in the solution, relation of thenumber of articles to the amount of carrying agent, amount of solution,times and temperatures of operation, and all such factors, may be widelyvaried to meet particular conditions of surface, size of articles, etc.,without departure from the fundamentals of the invention.

Assuming that the articles to be polished are to be tooth brush handlesof pyroxylin plastic, 1- provide for each two bushels of tooth brushhandles, two bushels of carrier devices of small size (conveniently hardwood shoe pegs whichare of rectangular cross section and about long byA, thick and A wide), seven ounces of a solution of what I forconvenience term an adherent or associating medium, and one ounce ofkieselguhr. The adherent solution may desirably shellac wax 2, bleachedbeeswax 2, and turpentine 38. For the turpentine, which serves merely asa solvent for the wax, may be substituted an equivalent such as toluolor other substances which will readily suggest themselves to thosefamiliar with the art of dis-' solving wax. If desired, camphor in smallamount may be added, or substituted in part for the turpentine, as apossible aid in the dryin which occurs in the cooling step referred toliriefiy above and to be hereafter described in detail. in the drying.The mixture is heated to dissolve the wax, say to 150 F., thekiesolgulll stirred in, and the mixture kept hot to insure the continuedsolution of the wax.

Preferably prior to the mixing of the articles with the shoe pegs, theshoe pegs are thoroughly sprinkled with the mixture of wax solution andkieselguhr, although obviously, the solution, the pegs, the articles,and the kieselguhr may be mixed in any order desired, the order ofmixing having no primary relation to the invention. The con1- pletemixture is now tumbled in a horizontal tumbling barrel, the barrel beingdesirably polygonal, say hexagonal, in cross section and of such size(say two and one-half feet in diameter by three feet long) that themixture does not fill the same over one-half or twothirds full. Therotation speed may, under ordinary circumstances, be from 30 to 40revolutions per minute, and the time from 9 to 12 hours. Obviously thesefactors depend upon the particular articles, etc., and will be varied ascircumstances require, by the particular operator to obtain maximumbenefits. As in the usual tumbling barrel, the same is provided with aside opening (say of about two square feet) for the introduction andremoval of the articles, such opening having a closed cover; but I alsoprovide a screen cover for use in conjunction with the cooling anddrying operation now to be described.

Somewhat prior, say one hour prior, to the end time of the tumblingoperation, the tumbling is temporarily discontinued, the ordinaryclosure of the barrel removed, and the screen cover substituted; andthen the tumbling operation is resumed for the remainder of the tumblingtime. Upon the removal of the usual cover, at the temporarydiscontinuing of the tumbling, it will be found that the interiortemperature of the barrel is high, sa 150 F., due, apparently, to theinternal friction of the mass (and a raised temperature is desirableduring the primary tumbling).

In particular accordance with my invention, I have found that thecooling of the mass and a short continued tumbling, as already indicatedwill result in the abolishing of the objectionable clouding beforementioned, and will give the high gloss not be- The shellac wax is alsoan aid.

fore procurable. The rotation of the barrel, and the consequent shiftingof the mass brings about an air pumping action in the barrel whicheffectively cools the contents and, in a species of drying actionremoves solvent vapors such as turpentine. Just what the ratio ofprimary tumbling to secondary tumbling should be, will, obviously dependon articular circumstances; the general rule is tiat the cooling and anddrying tumbling should be carried on long enough to remove the cloudingand give the desired burnishing. Under ordinary circumstances and forgoods of the type indicated, in a total tumbling of 12 hours, the secondtumbling may be about '1 hour.

In explanation of the action occurring in the cooling step, I may saythat, so far as appears, when the mass cools, giving the adherent atendency to precipitate, and the solvent vapors are removed from thebarrel, the adherent which is present on the articles in the form of acloud, or may be as distinct particles, assumes such a condition that asthe tumbling continues the carriers, or shoe pegs, are able to removethe adherent from the articles. It may be, also, that the cooling anddrying so effect the adherent, both that on the articles and that on thecarriers, that the tendency of the adherent to adhere to the carriers,as distinguished from the articles, is enhanced. In any case, theultimate result is that the adherent becomes entirely removable from thearticles in the final tumbling.

Furthermore, with the adherent removed from the articles and, it may beassumed, re-

disposed upon the carriers, the carriers and kieselguhr are in idealcondition for exerting a delicate burnishing action on the goods, havingin consideration the fact that the previous tumbling has smoothed thesurface of the oods to such a condition that burnishing is a practicalpossibility.

As will be understood by those skilled in the art, additional solution,either containing wax or not as circumstances require, may be suppliedto the shoe pegs, either during the tumbling operation, or between theuse of the pegs for one tumbling operation, and another tumblingoperation on another load of articles. There is practically no loss ofwax or kieselguhr from the mass; and obviously there is no loss of pegssince the screen of the barrel is sufiiciently small mesh to insure theretaining of the mass in the barrel during the tumbling.

I claim 1. In the polishing of articles, the method which com rises:tumbling the articles in the presence 0 an abrasive, carriers for theabrasive, and a heated mixture of anadherent for associating theabrasive and the carriers, and a liquid carrier for the adherent, suchtumbling being continued until the polishing is substantially completed,and then cooling the mass and continuing the tumbling for a short timewith the mass cooled.

2. In the polishing of articles, the method which comprises :-tumblinthe articles in a closed tumbling barrel in e presence of an abrasive,carriers for the abrasive and wax and a solvent therefor, such tumblingbeing continued until the polishing is substantially com leted, openingthe barrel and screenm the. arrel thereby to provide for coolm o I themass, and continuing the tumbling or a short time with the barrelscreened and the contents cooled.

3. In the polishing of articles, the method which comprises :tumblingthe articles in thepresence of abrasive carriers and a heated mixtureincluding (a) a solution comprising a waxy constituent and a solventtherefor in substantially the proportions 16: 38, and (b) an abrasive,the proportion of abrasive to solution being substantially 1:7, suchtumbling being continued until the polishing is substantially completed,and then coolin the mass and continuing the 'tumblingfor a s ort timewith the mass cooled.

4. In the polishing of articles, the method 1 which comprises :-tumblingthe articles in the presence of abrasive carriers, and a heated mixtureincludin (a) a solution comprising,

in parts-by-weig t proportion, ellow beeswax 12, shellac wax 2, bleachebeeswax 2, and a compound of the class comprisin toluol and turpentine38, and (b) kiesel I r,

as the proportion of kieselguhrtosolution g substantiall 1:7, suchtumbling being co tinned unti the polishing is substantiall completed,and then ooohng the mass contlnuing the tumbling for a short time withthe mass caged. ,f I

ntestimonyw ereo m si ature.

FREbERICE Libra.

